The international symposium « Agricultural Weeds and Plant Invaders » was initiated in 2006 and takes place once every three years in a European country (Portugal in 2006, Croatia in 2008, and Switzerland in 2011). This event brings together over 100 scientists and managers who share a strong interest in the Biology, Ecology and methods of controlling invasive plants in cultivated and natural habitats as well as urban areas. Objectives of the 4th symposium are: Strengthening interactions between all fields for the management of invasive plants (e.g., ragweed) by facilitating exchanges between the researchers in basic and applied research, and managers and action agencies in the field; Broadening the scope of this conference to include the entire Mediterranean basin where the agronomical and environmental concerns are similar those of the southern Europe; and, Bridging the fields of invasion biology science and social and human sciences. [Information of the supplier, modified]